[m-rev.] for review: improve documentation of --fully-strict

[Ian MacLarty]

On Mon, Sep 24, 2007 at 04:52:27PM +1000, Julien Fischer wrote:
>
> On Mon, 24 Sep 2007, Ian MacLarty wrote:
>
>> On Mon, Sep 24, 2007 at 03:44:40PM +1000, Julien Fischer wrote:
>>>
>>> On Mon, 24 Sep 2007, Ian MacLarty wrote:
>>>
>>>> On Mon, Sep 24, 2007 at 03:02:06PM +1000, Julien Fischer wrote:
>>>>>
>>>>> On Fri, 21 Sep 2007, Ian MacLarty wrote:
>>>>>
>>>>>> Estimated hours taken: 0.1
>>>>>> Branches: main
>>>>>>
>>>>>> compiler/options.m:
>>>>>> doc/user_guide.texi:
>>>>>> 	Document that --no-fully-strict also replaces det goals that produce
>>>>>> 	no outputs with `true' and goals that always fail with `fail'.
>>>>>
>>>>> simplify.m only does such replacements when when the goal is not impure
>>>>> however.
>>>>>
>>>>
>>>> Okay, I'll mention that the goal should not be impure.
>>>>
>>>>>> 	Also change the documented option to --no-fully-strict instead
>>>>>> 	of --fully-strict, because --fully-strict is the default.
>>>>>> 	XXX Should it be the default?
>>>>>
>>>>> I think yes; it's the least surprising choice.
>>>>>
>>>>
>>>> The reference manual says the following:
>>>>
>>>> The University of Melbourne Mercury implementation offers eight
>>>> different semantics, which can be selected with different
>>>> combinations of the @samp{--no-reorder-conj}, @samp{--no-reorder-disj},
>>>> and @samp{--fully-strict} options.  (The @samp{--fully-strict} option
>>>> prevents the compiler from improving completeness by optimizing away
>>>> infinite
>>>> loops or calls to @code{require.error/1} or @code{exception.throw/1}.)
>>>> The default semantics are the commutative semantics.  Enabling all of
>>>> these
>>>> options gives you the strict sequential semantics.  Enabling just some
>>>> of them gives you a semantics somewhere in between.
>>>>
>>>> This seems to suggest that the default is supposed to be
>>>> --no-fully-strict.
>>>>
>>>> Shall I change the reference manual too then?
>>>
>>> Yes; I think all you need to do is change the sense of the parenthesised
>>> setence that begins "The @samp{--fully-string} option ..." to "... allows
>>> the
>>> compiler to improve completeness ...".
>>>
>>
>> Wouldn't the default semantics now be the *strict* commutative semantics?
>
> Isn't that what they are anyway?
>

Well the reference manual currently says that the default semantics
are the "commutative semantics", not the "strict commutative semantics".  
As I understand it goals can't be deleted in the strict commutative
semantics, but in other commutative semantics (such as the one given by
--no-fully-strict) they can, as long as they are at least as complete as
the strict commutative semantics.

Have I got that right?

Ian.
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